Code of Federal Regulations Title 21. Food and Drugs § 21.177.1635 Poly(p-methylstyrene) and rubber-modified poly(p-methylstyrene)

(1) Poly(p-methylstyrene) (CAS Reg. No. 24936–41–2) polymer produced by the polymerization of p-methylstyrene.

(2) Rubber-modified poly(p-methylstyrene) (CAS Reg. No. 33520–88–6) polymer produced by combining styrene-butadiene copolymer and/or polybutadiene with poly(p-methylstyrene), either during or after polymerization of the poly(p-methylstyrene), such that the finished polymers contain not less than 75 weight percent of total polymer units derived from p-methylstyrene) monomer.

(1) Poly(p-methylstyrene) basic polymers identified in paragraph (a)(1) of this section shall contain not more than 1 weight percent of total residual p-methystyrene monomer, as determined by a gas chromatographic method titled, “Gas Chromatographic Determination of PMS and PET in PPMS Basic Polymers,” which is incorporated by reference. Copies are available from the Center for Food Safety and Applied Nutrition (HFS–200), Food and Drug Administration, 5001 Campus Dr., College Park, MD 20740, or available for inspection at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202–741–6030, or go to:  http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

(2) Rubber-modified poly(p-methylstyrene) basic polymers identified in paragraph (a)(2) of this section shall contain not more than 0.5 weight percent of total residual p-methylstyrene monomer, as determined by the method identified in paragraph (c)(1) of this section.